JP2010151596A - Method for treating radioactive metal waste - Google Patents
Method for treating radioactive metal waste Download PDFInfo
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- JP2010151596A JP2010151596A JP2008329688A JP2008329688A JP2010151596A JP 2010151596 A JP2010151596 A JP 2010151596A JP 2008329688 A JP2008329688 A JP 2008329688A JP 2008329688 A JP2008329688 A JP 2008329688A JP 2010151596 A JP2010151596 A JP 2010151596A
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- 230000002285 radioactive effect Effects 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims abstract description 46
- 239000010814 metallic waste Substances 0.000 title claims abstract description 42
- 238000005202 decontamination Methods 0.000 claims abstract description 90
- 229910052751 metal Inorganic materials 0.000 claims abstract description 87
- 239000002184 metal Substances 0.000 claims abstract description 87
- 230000003588 decontaminative effect Effects 0.000 claims abstract description 82
- 150000007933 aliphatic carboxylic acids Chemical class 0.000 claims abstract description 37
- 239000007788 liquid Substances 0.000 claims abstract description 27
- 238000005868 electrolysis reaction Methods 0.000 claims abstract description 16
- -1 platinum group metals Chemical class 0.000 claims abstract description 16
- 150000003839 salts Chemical class 0.000 claims abstract description 16
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical group [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims abstract description 12
- 238000009390 chemical decontamination Methods 0.000 claims abstract description 9
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910044991 metal oxide Inorganic materials 0.000 claims abstract description 7
- 239000000758 substrate Substances 0.000 claims abstract description 5
- 150000001735 carboxylic acids Chemical class 0.000 claims abstract 3
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- 235000019253 formic acid Nutrition 0.000 claims description 42
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 38
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical group OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 18
- 230000008929 regeneration Effects 0.000 claims description 16
- 238000011069 regeneration method Methods 0.000 claims description 16
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- 238000003672 processing method Methods 0.000 claims description 7
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- 238000000151 deposition Methods 0.000 claims description 2
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- 239000012857 radioactive material Substances 0.000 claims description 2
- HTXDPTMKBJXEOW-UHFFFAOYSA-N dioxoiridium Chemical compound O=[Ir]=O HTXDPTMKBJXEOW-UHFFFAOYSA-N 0.000 claims 1
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- 238000010306 acid treatment Methods 0.000 abstract description 2
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- 238000004090 dissolution Methods 0.000 description 6
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- 229910052719 titanium Inorganic materials 0.000 description 4
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
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- 239000004568 cement Substances 0.000 description 3
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- 150000004706 metal oxides Chemical class 0.000 description 3
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- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 2
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- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 1
- JAJIPIAHCFBEPI-UHFFFAOYSA-N 9,10-dioxoanthracene-1-sulfonic acid Chemical compound O=C1C2=CC=CC=C2C(=O)C2=C1C=CC=C2S(=O)(=O)O JAJIPIAHCFBEPI-UHFFFAOYSA-N 0.000 description 1
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- BDAGIHXWWSANSR-UHFFFAOYSA-M Formate Chemical compound [O-]C=O BDAGIHXWWSANSR-UHFFFAOYSA-M 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
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- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 1
- 235000013980 iron oxide Nutrition 0.000 description 1
- PQQAOTNUALRVTE-UHFFFAOYSA-L iron(2+);diformate Chemical compound [Fe+2].[O-]C=O.[O-]C=O PQQAOTNUALRVTE-UHFFFAOYSA-L 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
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- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
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- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
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- Treatment Of Water By Oxidation Or Reduction (AREA)
- Water Treatment By Electricity Or Magnetism (AREA)
Abstract
Description
本発明は炭素鋼等の鉄系の放射性金属廃棄物の新規な処理方法に関する。 The present invention relates to a novel method for treating ferrous radioactive metal waste such as carbon steel.
原子力発電所等で発生する放射能で表面が汚染された放射性金属廃棄物の除染方法として、放射性金属廃棄物の汚染度の高い表面部を酸により溶解して再利用可能な許容汚染レベルまで金属を除染するとともに、溶解して生成させた金属塩や水酸化物等の汚染度の高い沈殿物は、ろ過分離して、ろ滓をセメントで固めて処分する化学的除染方法がある。この化学的除染方法は、原子力発電所から排出される廃棄物を、再利用可能な汚染レベルまで容易に除染することができるとともに、二次放射性廃棄物の発生量も少ない。このため、放射性廃棄物として法規制を受け、所定場所に保管した後に、法規制に適合した処分をすることが必要な放射性廃棄物の発生量を大幅に低減できるとともに、省資源にもつながる。 As a decontamination method for radioactive metal waste whose surface is contaminated with radioactivity generated at nuclear power plants, etc., the highly contaminated surface of radioactive metal waste is dissolved with acid to an acceptable contamination level that can be reused. There is a chemical decontamination method that decontaminates metals, and precipitates that are highly contaminated, such as metal salts and hydroxides that are generated by dissolution, by filtering and separating, and solidifying the filter cake with cement. . This chemical decontamination method can easily decontaminate waste discharged from a nuclear power plant to a reusable contamination level, and the amount of secondary radioactive waste generated is small. For this reason, it is possible to significantly reduce the amount of radioactive waste that is required to be disposed of in compliance with the laws and regulations after receiving the laws and regulations as radioactive wastes and storing them in a predetermined place, as well as saving resources.
そして、酸として、ギ酸等の脂肪族カルボン酸を使用すれば、酸化により水と炭酸ガスに分解することができ、使用済除染液を再使用でき液廃棄物の発生が殆どない点等において、無機酸に比して有利である。 If an aliphatic carboxylic acid such as formic acid is used as the acid, it can be decomposed into water and carbon dioxide by oxidation, the used decontamination solution can be reused, and there is almost no generation of liquid waste. This is advantageous compared to inorganic acids.
例えば、特許文献1(米国特許5386078号)で、ギ酸により化学的除染をする処理法が提案されている。なお、特許文献2にも同様な技術が記載されている。
For example, Patent Document 1 (US Pat. No. 5386078) proposes a treatment method for chemical decontamination with formic acid.
当該米国特許のアブストラクトを和訳して、以下に引用する。 The abstract of the US patent is translated into Japanese and is cited below.
「放射性汚染金属を除染する方法。放射性汚染金属(対象金属)を第一浴に投入して、該第一浴の非放射性のギ酸水溶液に、ギ酸濃度が化学量論に一致した量を消費した水溶液になるまで接触させる。次に、対象金属を同じ化学組成を有する第二浴に投入する。第二浴の非放射性の水溶液にも同様に、化学量論に一致した量のギ酸が消費されるまで対象金属を接触させることが望ましい。ギ酸濃度は、約0.3mol/Lとする。これらの操作を繰り返して許容汚染率(例えば、0.37Bq/cm2)になるまで繰り返す。放射性金属水酸化物乃至酸化物(汚染スラッジ)が沈降分離される。そして、これらの汚染スラッジはセメントで固化されてさらに除染されていく。」 “Method of decontaminating radioactive contamination metals. Putting radioactive contamination metals (target metals) into the first bath and consuming a non-radioactive formic acid solution in the first bath whose formic acid concentration matches the stoichiometry. Next, the target metal is put into a second bath having the same chemical composition, and the non-radioactive aqueous solution in the second bath similarly consumes a stoichiometric amount of formic acid. The formic acid concentration should be about 0.3 mol / L, and repeat these operations until an acceptable contamination rate (for example, 0.37 Bq / cm 2 ) is reached. Oxides or oxides (contaminated sludge) are settled and separated, and the contaminated sludge is solidified with cement and further decontaminated. "
さらに、非特許文献1(kohli & Hanulik「汚染金属廃棄のための新規な除染方法(AN INNOVATIVE CHEMICAL DECONTAMINATION SYSTEM FOR FREE RELEASE OF METALS)」)における要約(abstract)には上記方法について、次の記載(翻訳)がある。 Furthermore, in the abstract in Non-Patent Document 1 (kohli & Hanulik “AN INNOVATIVE CHEMICAL DECONTAMINATION SYSTEM FOR FREE RELEASE OF METALS”), the above method is described as follows. (Translation).
「廃棄可能基準までの経済的な化学的除染方法が開発されている。当該方法「DECOFOR」(特許されたギ酸処理に基づく)は、ニッケル、鉛、銅、炭素鋼やアルミニウム等の広範な金属に適用可能である。本処理は、経済的で、毒性薬剤を使用せず、液体廃棄物は生成されずに最小限の固体廃棄物が生成されるのみである、除染しない水が循環される、等において長所を有する。本方法は、除染処理前後の除染率を測定し、そして、個々に適合可能な全体的な除染技術に展開するための金属試料の精確な採取技術も含む。除染は迅速で効率的である。即ち、室温における除去速度は、酸濃度が0.5〜1.0%において、Pb,Cu:1.0mg/(cm2・min);Al,炭素鋼,Ni:0.1〜1.0mg/(cm2・h)である。この処理法は、U.S. Department of Energy (DOE) 施設内や他の廃棄プロジェクトにおける在庫汚染金属の廃棄基準までの除染に適用できるものである。」 “Economic chemical decontamination methods up to disposable standards have been developed. The method“ DECOFOR ”(based on patented formic acid treatment) is widely used for nickel, lead, copper, carbon steel, aluminum, etc. Applicable to metal. This treatment is advantageous in that it is economical, does not use toxic drugs, produces only minimal solid waste without producing liquid waste, and circulates non-decontaminated water. Have. The method also includes an accurate collection technique for metal samples to measure the decontamination rate before and after the decontamination process and develop into an overall decontamination technique that is individually adaptable. Decontamination is quick and efficient. That is, the removal rate at room temperature is Pb, Cu: 1.0 mg / (cm 2 · min); Al, carbon steel, Ni: 0.1 to 1.0 mg / (cm 2 · h) at an acid concentration of 0.5 to 1.0%. is there. This treatment method can be applied to decontamination within the US Department of Energy (DOE) facilities and other disposal projects to the disposal standards for contaminated metals. "
また、同じく、「III.除染方法の説明、A.DECOFORの基本原理、B.処理法の概括」の項には下記記載(和訳)がある。なお、訳文中の「Fig.1」は、本願の図1(翻訳図)として添付してある。 Similarly, in the section of “III. Explanation of decontamination method, A. Basic principle of DECOFOR, B. Summary of treatment method”, there is the following description (Japanese translation). “Fig.1” in the translation is attached as FIG. 1 (translation diagram) of the present application.
「A.DECOFORの基本原理:
ギ酸(HCOOH)は、殆どの金属と金属酸化物を溶解してギ酸塩となる。ギ酸は溶解度が非常に高い。例えば、2molのギ酸は1molのFeを溶解してギ酸鉄を生成する。その他の反応生成物は存在しないので、この反応は化学量論的に精確に制御でき、結果的に、除染に必要なギ酸量及び廃液量を最小限とすることができる。殆どのギ酸金属塩は水溶性であるため、除染液から溶解金属を回収するとともに水を再生して再使用することが容易となる。
“A. The basic principle of DECOFOR:
Formic acid (HCOOH) dissolves most metals and metal oxides to form formate. Formic acid has a very high solubility. For example, 2 mol of formic acid dissolves 1 mol of Fe to produce iron formate. Since no other reaction products are present, the reaction can be controlled stoichiometrically and, as a result, the amount of formic acid and waste liquid required for decontamination can be minimized. Since most metal formate salts are water-soluble, it is easy to recover the dissolved metal from the decontamination solution and recycle and reuse the water.
ある金属群は他の金属群より水に溶け易い。例えば、鉛の溶解速度は、pH0.5前後では実質的に酸濃度に無関係である。しかし、H2O2の濃度は反応速度に関係する。鉛は、2%を超える濃度でのH2O2の激しい分解により溶解する。したがって、本処理法では、当初H2O2濃度3%で開始し、除染サイクルを通じて、丁度2%を超える濃度に維持する。金属表面におけるH2O2の活発な分解は金属表面における除染効率を機械的に高める。鉛は大部分がPb2+として溶けるが、部分的に酸化して酸化物(PbO,PbO2)となる。溶解反応は、酸が消費された後、H2O2及びH+イオンもなくなって停止する(pH=6〜7)。 Some metal groups are more soluble in water than other metal groups. For example, the dissolution rate of lead is substantially independent of acid concentration around pH 0.5. However, the concentration of H 2 O 2 is related to the reaction rate. Lead dissolves by vigorous decomposition of H 2 O 2 at concentrations greater than 2%. Therefore, the treatment method starts with an initial H 2 O 2 concentration of 3% and maintains a concentration just above 2% throughout the decontamination cycle. Active decomposition of H 2 O 2 on the metal surface mechanically increases the decontamination efficiency on the metal surface. Most of lead dissolves as Pb 2+ , but is partially oxidized to oxides (PbO, PbO 2 ). The dissolution reaction stops after the acid is consumed, with no H 2 O 2 and H + ions (pH = 6-7).
B.方法の概括:
処理体系の概括及び物質流れを、Pbを例とするFig.Iに示す。DECOFOR除染処理は、汚染金属を希釈ギ酸溶液に短時間浸漬する工程を含む。当該酸溶液を汚染金属にスプレーしてもよい。ギ酸が化学量論的に消費された後、汚染表面層を水で濯いで除去する。化学量論的に消費された溶液(使用済み溶液)は、酸化剤としてのH2O2で再生することができる。酸化剤は不溶性化合物を沈殿させる。該使用済溶液に当初濃度となるようにギ酸を添加すれば、当該酸溶液は再使用可能である。溶解金属を含む当該溶液は、化学的に又は電気化学的に処理して、金属を回収する。電解後のギ酸溶液は再利用のために除染タンクに戻す。本処理法は水と除染薬剤の閉サイクルで行われることとなる。したがって、そこには廃棄液がなく、二次固体廃棄物が最小限となる(金属又は金属酸化物としての当初金属の0.01〜0.1%)。」
B. Method summary:
An overview of the treatment system and the material flow are shown in Fig. Shown in I. The DECOFOR decontamination process includes a step of immersing the contaminated metal in a diluted formic acid solution for a short time. The acid solution may be sprayed onto the contaminated metal. After the formic acid is consumed stoichiometrically, the contaminated surface layer is rinsed away with water. Stoichiometrically consumed solution (spent solution) can be regenerated with H 2 O 2 as oxidant. Oxidizing agents precipitate insoluble compounds. If formic acid is added to the used solution so as to have an initial concentration, the acid solution can be reused. The solution containing the dissolved metal is treated chemically or electrochemically to recover the metal. The formic acid solution after electrolysis is returned to the decontamination tank for reuse. This treatment method is performed in a closed cycle of water and a decontamination agent. Therefore, there is no waste liquid and there is minimal secondary solid waste (0.01-0.1% of the original metal as metal or metal oxide). "
そして、上記の特許文献1・2及び非特許文献1等に記載の鉄系の放射性金属廃棄物の処理方法は、いずれも、基本的に、ギ酸等の有機酸(脂肪族カルボン酸)によって鉄表面に付着生成した放射能汚染層を、その層の下にある金属母材を溶解することで、前記放射能汚染層を剥離除染する方法である。
And all of the processing methods of the iron-type radioactive metal wastes described in
そして、除染済みの除染廃液は、H2O2等の酸化剤で有機酸を水と二酸化炭素に分解して、水を再利用する。 The decontamination already decontamination waste liquid, by decomposing the organic acid into water and carbon dioxide with an oxidizing agent such as H 2 O 2, to recycle the water.
さらに、その際発生する不溶性化合物(金属水酸化物)等の二次廃棄物の発生を抑制するために、電気化学的に処理(電解処理)して金属を陰極に電着捕集することが提案されている(非特許文献1)。 Furthermore, in order to suppress the generation of secondary waste such as insoluble compounds (metal hydroxide) generated at that time, the metal can be electrodeposited and collected on the cathode by electrochemical treatment (electrolytic treatment). It has been proposed (Non-Patent Document 1).
しかし、該非特許文献1では、再生工程でFeを電解槽で電析回収することについては記載されていない。即ち、PbやCu以外の金属については、電析回収が不可乃至困難であることを示唆している。 However, the non-patent document 1 does not describe that Fe is electrodeposited and recovered in the electrolytic cell in the regeneration process. That is, for metals other than Pb and Cu, it is suggested that electrodeposition recovery is impossible or difficult.
非特許文献1のp1881左欄下5行〜同右欄6行頁の「再生(Regeneration)」の項には、下記翻訳文の如く記載されている。 Non-Patent Document 1 describes the following translation in the “Regeneration” section on page 5 of the lower left column of p1881 to page 6 of the right column.
「溶解金属(Fe、Cu、Al、Pb、Ni)は金属水酸化物として沈殿する。溶液からの放射性核種は金属水酸化物の表面に吸着している。沈降・ろ過後、清浄水が回収され除染ループの先頭に戻す。固状沈殿物とろ滓はセメントで固化される。代わりに、PbとCuは、電解槽の鉛又は銅を、金属又は酸化物として、それぞれ陰極又は陽極に析出させて回収できる。電解後の酸溶液は、除染タンクに戻して再使用する。」 “Dissolved metals (Fe, Cu, Al, Pb, Ni) precipitate as metal hydroxides. Radionuclides from the solution are adsorbed on the surface of the metal hydroxides. After sedimentation and filtration, clean water is recovered. The solid precipitate and filter cake are solidified with cement, instead Pb and Cu are deposited on the cathode or anode as electrolytic metal lead or copper, respectively, as metal or oxide. The acid solution after electrolysis is returned to the decontamination tank for reuse. "
なお、本発明の特許性に影響を与えるものではないが、特許文献3に放射性金属廃棄物の処理方法に関連する技術として、下記構成の放射性金属スラッジの処理方法が記載されている(特許請求の範囲等)。 Although not affecting the patentability of the present invention, Patent Document 3 describes a method for treating radioactive metal sludge having the following configuration as a technique related to the method for treating radioactive metal waste (patent claim). Range).
「放射能で表面の汚染された放射性金属廃棄物を、中性塩電解液中で電解溶解して放射性金属廃棄物表面の放射性物質を除去した際に生成する金属水酸化物スラッジをシュウ酸、ギ酸、クエン酸のうち少なくとも1種以上の有機酸を含む洗浄液によって、金属イオンとして溶解させ、有機酸は電解操作により酸化分解するとともに、溶解した金属イオンを陰極に伝席させた、嵩の小さな金属塊として回収することを特徴とする放射性金属スラッジの処理方法。」 “Oxidized metal hydroxide sludge generated when the radioactive metal waste contaminated with radioactive surfaces is electrolyzed and dissolved in neutral salt electrolyte to remove the radioactive material on the surface of the radioactive metal waste. A solution containing at least one organic acid of formic acid and citric acid is dissolved as a metal ion, and the organic acid is oxidatively decomposed by an electrolytic operation, and the dissolved metal ion is transmitted to the cathode, and has a small bulk. A method for treating radioactive metal sludge, characterized by being collected as a metal mass. "
しかし、当該方法は、弱酸を使用しての除染処理ではなくて、中性塩電解液中での除染処理を前提としており除染処理方法が異質であるとともに、有機酸の酸化分解も電解操作によるものであり異質である。
本発明は、上記にかんがみて、鉄系放射性金属廃棄物を酸化分解可能な脂肪族カルボン酸(有機酸)で酸処理する方法において、使用済除染液(劣化除染液)の実用的な再生使用ができ、さらには、脂肪族カルボン酸金属塩の酸化分解に際して生成する放射性金属廃棄物(水酸化沈殿物)の発生量を可及的に低減可能な鉄系放射性金属廃棄物の処理方法を提供することを目的とする。 In view of the above, the present invention is a practical method of using a used decontamination solution (degradation decontamination solution) in a method of acid-treating an iron-based radioactive metal waste with an oxidatively decomposable aliphatic carboxylic acid (organic acid). A method for treating ferrous radioactive metal waste that can be reused and that can reduce as much as possible the amount of radioactive metal waste (hydroxylated precipitate) generated during the oxidative decomposition of aliphatic carboxylic acid metal salts The purpose is to provide.
上記非特許文献1で電解再生については鉛と銅についてのみ記載されている理由は、下記の如くである。 The reason why only non-patent document 1 describes electrolytic regeneration only for lead and copper is as follows.
前述の翻訳文に記載の如く、ギ酸の除染液に過酸化水素を添加し、2%以上の過酸化水素濃度で鉛が良く水に溶けることを利用して、鉛系の放射性金属廃棄物の除染を行うことを前提としている。 As described in the above translation, lead-based radioactive metal waste is obtained by adding hydrogen peroxide to the formic acid decontamination solution and using the fact that lead dissolves well in water at a hydrogen peroxide concentration of 2% or more. It is assumed that decontamination will be performed.
除染後電解により放射性金属(鉛)を陰極で回収し、陽極では鉛・銅の酸化物を回収する。そして、この陽極での鉛・銅の酸化に際して、過酸化水素が分解して陽極での金属酸化物(PbO2)の酸素(O2)の供給源となるともに、水素イオン(H+)が発生して、有機酸を再生させる。ギ酸の場合を例にとると、反応式は下記の如くであると考えられる。 After decontamination, radioactive metal (lead) is recovered at the cathode by electrolysis, and lead and copper oxides are recovered at the anode. During the oxidation of lead and copper at the anode, hydrogen peroxide is decomposed to become a source of oxygen (O 2 ) of the metal oxide (PbO 2 ) at the anode, and hydrogen ions (H + ) To regenerate the organic acid. Taking the case of formic acid as an example, the reaction formula is considered as follows.
H2O2→2H++O2+2e−
Pb2++O2→PbO2+2e−
HCOO−+H+→HCOOH
しかし、放射性金属が鉛や銅以外の鉄の場合は、過酸化水素の存在下で、鉄イオン(Fe2+)を含むと、下記フェントン反応により生成するヒドロキシラジカルが、有機酸の酸化分解を促進するように作用して、脂肪族カルボン酸の電解再生が困難と考えられる。ギ酸の場合を例にとると、反応式は下記の如くであると推定される。
H 2 O 2 → 2H + + O 2 + 2e −
Pb 2+ + O 2 → PbO 2 + 2e −
HCOO − + H + → HCOOH
However, when the radioactive metal is iron other than lead or copper, if it contains iron ions (Fe 2+ ) in the presence of hydrogen peroxide, the hydroxy radicals generated by the following Fenton reaction promote the oxidative decomposition of organic acids. Thus, it is considered that the electrolytic regeneration of the aliphatic carboxylic acid is difficult. Taking the case of formic acid as an example, the reaction equation is estimated as follows.
フェントン反応:H2O2+Fe2+→Fe3++HO−+・OH
酸化分解:HCOO−+・OH→H2O+CO2
また、過酸化水素を存在させない場合には、電解酸化されると考えられる(特許文献3段落0009〜0010参照)。
Fenton reaction: H 2 O 2 + Fe 2+ → Fe 3+ + HO − + · OH
Oxidative decomposition: HCOO − + · OH → H 2 O + CO 2
Moreover, when hydrogen peroxide is not present, it is considered that electrolytic oxidation is performed (see Patent Document 3, paragraphs 0009 to 0010).
このように、鉄とギ酸等の脂肪族カルボン酸で溶解処理した除染液を、過酸化水素の存在の有無に関係なく、電解槽で金属回収とともに脂肪族カルボン酸の再生を行なうことは、従来行なわれていない。 In this way, the decontamination solution dissolved with an aliphatic carboxylic acid such as iron and formic acid, regardless of the presence or absence of hydrogen peroxide, recovering the aliphatic carboxylic acid together with metal recovery in the electrolytic cell, This has not been done in the past.
上記考察から、脂肪族カルボン酸の再生を行なうためには、過酸化水素以外のH+供給源が必要となると考えて、鋭意開発に努力をした結果、鉄系の放射性金属廃棄物であっても、陽極としてイリジウム被覆電極等の白金族金属等で被覆されたものを用いれば、H+が供給でき、有機酸の電解再生が可能であることを知見して下記構成の本発明に想到し得た。 From the above consideration, it was thought that in order to regenerate the aliphatic carboxylic acid, an H + supply source other than hydrogen peroxide would be required. In addition, if an anode coated with a platinum group metal such as an iridium-coated electrode is used, H + can be supplied and electrolytic regeneration of an organic acid is possible. Obtained.
放射能で表面が汚染された鉄系の放射性金属廃棄物の処理方法であって、
該放射性金属廃棄物を、その金属塩が水溶性であり酸化分解可能な脂肪族カルボン酸を含む除染液に浸漬して、前記放射性金属廃棄物の表面部を脂肪族カルボン酸金属塩として前記除染液中に溶出させて除染を行う化学的除染操作を含む放射性金属廃棄物の処理方法において、
前記除染工程で発生する劣化除染液を電解して、陰極で前記カルボン酸金属塩の金属成分を析出させて回収するに際して、
陽極として導電性基体が白金族金属又は白金族金属酸化物で被覆されたものを使用して、脂肪族カルボン酸を電解再生させる、ことを特徴とする。
A method for treating ferrous radioactive metal waste whose surface is contaminated by radioactivity,
The radioactive metal waste is immersed in a decontamination solution containing an aliphatic carboxylic acid whose metal salt is water-soluble and oxidatively decomposable, and the surface portion of the radioactive metal waste is used as the aliphatic carboxylic acid metal salt. In a method for treating radioactive metal waste, including chemical decontamination operations, which are decontaminated by elution in a decontamination solution,
When electrolyzing the deteriorated decontamination solution generated in the decontamination step and depositing and collecting the metal component of the carboxylic acid metal salt at the cathode,
It is characterized in that an aliphatic carboxylic acid is electrolytically regenerated using a conductive base coated with a platinum group metal or platinum group metal oxide as an anode.
イリジウム等の白金族金属は、触媒として種々の活性を有しており、有機酸を含む水の分解において、効率よく酸素を発生させ、その結果水素イオンを得るための電極として、工業的に利用されている(商品カタログ「酸素発生用DSE:不溶性金属電極Dimentionally Stable Electrode」ペルメレック電極株式会社、2008年、3p)
本発明では、イリジウム等の白金族金属が同様な作用を奏していると考えられる。
Platinum group metals such as iridium have various activities as catalysts, and they are used industrially as electrodes for efficiently generating oxygen in the decomposition of water containing organic acids and consequently obtaining hydrogen ions. (Product Catalog “DSE for Oxygen Generation: Insoluble Metal Electrode Dimentionally Stable Electrode” Permelec Electrode Co., Ltd., 2008, 3p)
In the present invention, it is considered that a platinum group metal such as iridium has a similar effect.
劣化除染液を電解することにより、鉄系成分(Ni,Cr、Co等も含む。)は陰極に電析して回収されるとともに、脂肪族カルボン酸が再生される。このため、脂肪族カルボン酸金属塩の溶解濃度が低減する。この際のpH上昇により金属成分の溶解形態が変化して、水酸化物の沈殿が再溶解する。また、劣化除染液中の脂肪族カルボン酸金塩から金属成分が除去されて生じた脂肪族カルボン酸イオンに、電解により生じた水素イオンが結合して脂肪族カルボン酸を再生する。このため、劣化除染液のpHは低下し、脂肪族カルボン酸の濃度が上昇する。 By electrolyzing the deteriorated decontamination solution, iron-based components (including Ni, Cr, Co and the like) are electrodeposited on the cathode and recovered, and the aliphatic carboxylic acid is regenerated. For this reason, the dissolution concentration of the aliphatic carboxylic acid metal salt is reduced. At this time, the dissolution state of the metal component changes due to the increase in pH, and the hydroxide precipitate is redissolved. In addition, hydrogen ions generated by electrolysis are combined with aliphatic carboxylate ions generated by removing metal components from the aliphatic carboxylic acid gold salt in the decontamination solution to regenerate the aliphatic carboxylic acid. For this reason, the pH of the deteriorated decontamination liquid decreases and the concentration of the aliphatic carboxylic acid increases.
当該、電解処理後の劣化除染液は、適宜、脂肪族カルボン酸を補充して除染液として再使用できる。 The deterioration decontamination liquid after the electrolytic treatment can be reused as a decontamination liquid by appropriately supplementing the aliphatic carboxylic acid.
また、電解処理後の劣化除染液を、酸化剤により酸化処理すれば、脂肪族カルボン酸が分解して、最終的に廃棄する際に使用するイオン交換樹脂量を低減できる。また、電解により金属イオンを回収しているので、水酸化物の沈殿発生量も低減することができて、ろ過操作も容易となる。 Moreover, if the deterioration decontamination solution after electrolytic treatment is oxidized with an oxidizing agent, the amount of the ion exchange resin used when the aliphatic carboxylic acid is decomposed and finally discarded can be reduced. In addition, since metal ions are collected by electrolysis, the amount of hydroxide precipitates can be reduced, and the filtration operation is facilitated.
次に、図例に基づいて本発明を詳述する。図2は本発明方法の一態様を示すフローシートであり、図3は、本発明の方法で使用する除染装置ユニットの概略図である。ここでは、酸化分解可能な脂肪族カルボン酸としてギ酸を、酸化剤として水酸化物を、それぞれ使用する場合を主として例に採り説明する。 Next, the present invention will be described in detail with reference to the drawings. FIG. 2 is a flow sheet showing an embodiment of the method of the present invention, and FIG. 3 is a schematic view of a decontamination unit used in the method of the present invention. Here, the case where formic acid is used as the oxidatively decomposable aliphatic carboxylic acid and hydroxide is used as the oxidizing agent will be mainly described as an example.
該除染装置ユニットは、除染槽11と電解槽13とを備えるとともに、両槽の間には、除染槽11の除染液15を電解槽13に液送りする送りポンプ17を有する送り配管19(液送り手段)と、電解槽13に送液された除染液15を除染槽11へ液戻しする戻しポンプ21を有する戻し配管22(液戻し手段)とで連通されている。
The decontamination apparatus unit includes a
当然、除染槽11には、除染液15が充填され放射性金属廃棄物31が投入可能とされている。また、電解槽13は、電解用電源25と接続された陽極27と陰極29が除染液15に浸漬可能に配設されている。
Naturally, the
ここで、陽極27は、白金族金属で全体を形成してもよいが、白金族金属で全体を形成することはコスト的な見地から実際的ではない。このため、通常、安価な導電性基体を白金族金属又は白金族金属酸化物で被覆したものを使用する。
Here, the
上記導電性基体の材料としては、チタン、タンタル、ニオブ、ステンレス、カーボン系材料等を使用できるがチタンが望ましい。また、白金族金属としては、イリジウム、白金、パラジウム、ルテニウムおよびロジウムを使用することができる。これらの内で、チタンとイリジウムの組合わせのものが、市販品として容易に入手できる。 As a material for the conductive substrate, titanium, tantalum, niobium, stainless steel, carbon-based material, or the like can be used, but titanium is desirable. As the platinum group metal, iridium, platinum, palladium, ruthenium and rhodium can be used. Of these, a combination of titanium and iridium is readily available as a commercial product.
白金族金属は前述の如く、水を分解して水素イオン(H+)を供給する触媒作用を奏するため、脂肪族カルボン酸の再生を可能とする。他の導電体では、そのような触媒作用は期待できない。 As described above, the platinum group metal has a catalytic action of decomposing water and supplying hydrogen ions (H + ), so that the aliphatic carboxylic acid can be regenerated. With other conductors, such catalytic action cannot be expected.
また、陰極は、導電体であれば特に限定されず、鉄や銅等の金属導電体や、カーボン、セラミック等の非金属導電体を使用できる。 The cathode is not particularly limited as long as it is a conductor, and a metal conductor such as iron or copper, or a non-metal conductor such as carbon or ceramic can be used.
上記脂肪族カルボン酸としては、金属塩が水溶性であり酸化分解可能であれば特に限定されず、ギ酸、シュウ酸等を使用できる。これらの内で、鉄系金属に対する溶解性が高く、酸化分解も容易なギ酸が望ましい。なお、本発明者らは、クエン酸やマロン酸では、金属溶解が出来なかったことを確認している。 The aliphatic carboxylic acid is not particularly limited as long as the metal salt is water-soluble and can be oxidatively decomposed, and formic acid, oxalic acid, and the like can be used. Of these, formic acid is preferable because it is highly soluble in iron-based metals and easily oxidatively decomposes. In addition, the present inventors have confirmed that citric acid and malonic acid could not dissolve the metal.
次に、上記除染装置ユニットを用いての鉄系放射性金属廃棄物の処理方法(鉄系放射能汚染金属除染方法)について説明をする。 Next, the processing method (iron-type radioactive contamination metal decontamination method) of the iron-type radioactive metal waste using the said decontamination apparatus unit is demonstrated.
まず、汚染金属31の汚染層の厚さから反応モル数を予測し、浸漬時間を求めて、除染液15を充填した除染槽11を準備する。
First, the number of moles of reaction is predicted from the thickness of the contaminated layer of the contaminated
除染液15における脂肪族カルボン酸の濃度は、脂肪族カルボン酸の種類により異なるが、ギ酸の場合、0.217〜2.17mol/Lの範囲で適宜選定する。
The concentration of the aliphatic carboxylic acid in the
除染槽11の大きさは、汚染金属31の大きさにより異なるが、例えば、2〜6m3程度充填可能のものを通常使用する。汚染金属31の嵩は、0.5〜1.5m3程度とする。また、電解槽13の容量は、除染槽11で発生した汚染除染液を送液充填可能であれば特に限定されず、例えば、除染槽11の約1/6とする。
Although the size of the
そして、汚染金属31を浸漬用篭33に入れクレーン等で吊り下げて汚染金属31へ投入して、所定時間、浸漬させる。このときの浴温は、常温でもよいが、約60℃以上とすることが、反応速度的に望ましい。上限は、約80℃、望ましくは約65℃とする。高温になるにしたがって、昇温に要する時間が長くなるとともに、ギ酸成分が蒸気とともに系外へ逸散し易くなって望ましくない。
Then, the contaminated
また、浸漬(接触)時間は、温度、ギ酸濃度等により異なるが、通常、0.5〜2hとする。 Moreover, although immersion (contact) time changes with temperature, formic acid concentration, etc., it is normally set to 0.5-2h.
そして、汚染金属31の除染処理が終了したら、汚染金属31を除染槽11から引き上げる。ここで除染槽11内の除染液は、放射汚染金属の脂肪酸金属塩として溶解しているため、放射能汚染されたものとなっている。
When the decontamination process for the contaminated
当該汚染除染液を電解槽13へ送り配管19を介して送液・貯留する。電解槽13の電解用電源25をオンとして、電解再生を行なう。このとき陽極側ではH+が生成・供給されて脂肪族カルボン酸の電解再生が、陰極側では、鉄系金属陽イオンに電子が供与されて電析が行なわれる。
The contaminated decontamination solution is sent to the
そのときの各反応は、脂肪族カルボン酸がギ酸で、鉄系金属がFeの場合の反応式は下記の如くであると推定される。 Each reaction at that time is estimated to be as follows when the aliphatic carboxylic acid is formic acid and the iron-based metal is Fe.
電解再生反応(陽極):HC00-+H+ → HCOOH
電析反応(陰極):Fe2++2e−→ Fe
なお、汚染金属廃棄物がステンレスのような鉄系の場合、CoやNi、Cr等も含んでいるが、それらも、Feの場合と同様に電析する。
Electrolytic regeneration reaction (anode): HC00 − + H + → HCOOH
Electrodeposition reaction (cathode): Fe 2+ + 2e − → Fe
In the case where the contaminated metal waste is iron-based such as stainless steel, it contains Co, Ni, Cr, etc., but these are also electrodeposited as in the case of Fe.
このときの電解条件は、例えば、電流密度0.0025〜0.01A/cm2とし、通電時間は10〜100hとする。 The electrolysis conditions at this time are, for example, a current density of 0.0025 to 0.01 A / cm 2 and an energization time of 10 to 100 h.
この電解再生により再生されたギ酸は、戻り配管22を介して除染槽11へ戻す。この際、通常、戻すことのできる除染液の量が不足するので、ギ酸及び水を補填して、除染槽11の除染液量を設定量とする。
The formic acid regenerated by this electrolytic regeneration is returned to the
そして、再度、汚染金属31を投入して除染処理(溶解処理)を行なう。上記各処理(操作)を繰り返すことにより、鉄系放射性金属廃棄物の処理を行う。
And again, the decontamination process (dissolution process) is performed by introducing the contaminated
また、電解槽では、陰極に汚染金属がある量以上電析して電解効率が低下してきた場合は、新しい陰極と取替える。使用済陰極は、放射性廃棄物の廃棄基準に従って廃棄する。 Also, in the electrolytic cell, if the electrolytic efficiency decreases due to electrodeposition of a certain amount of contaminating metal on the cathode, it is replaced with a new cathode. Dispose of used cathodes in accordance with the radioactive waste disposal standards.
なお、電解再生処理後の除染液を、除染液に戻さずに、図2の下段に示すごとく、過酸化水素を添加して、ギ酸を分解させるとともに放射性沈殿物(鉄酸化物)を生成させる処理を行ってもよい。使用済除染液(劣化除染液)の電解処理により汚染金属を電着回収したことにより、金属溶解成分が減少しているため、放射性沈殿物の生成量を大幅に減ずることができる。その結果、放射性沈殿物のろ過分離が容易になり、それらに起因する二次廃棄物の発生がなくなり、ギ酸分解により炭酸ガスと水に分解できるため、水の再利用も可能となる。 In addition, without returning the decontamination solution after the electrolytic regeneration treatment to the decontamination solution, as shown in the lower part of FIG. 2, hydrogen peroxide is added to decompose formic acid and radioactive precipitates (iron oxides). You may perform the process to produce | generate. Since the contaminated metal is electrodeposited and recovered by electrolytic treatment of the used decontamination liquid (degradation decontamination liquid), the amount of dissolved metal components is reduced, so that the amount of radioactive precipitates generated can be greatly reduced. As a result, the radioactive precipitates can be easily separated by filtration, the generation of secondary waste due to them is eliminated, and water can be reused because it can be decomposed into carbon dioxide and water by formic acid decomposition.
原子力発電所から出た放射性金属廃棄物(炭素鋼廃棄:約600g)を使用して、除染液240L(開始時ギ酸濃度:2%(0.435mol/L)を用いて、2h浸漬処理(除染処理)を行なって、汚染除染液(劣化除染液)の試料液240Lを調製した。 Using radioactive metal waste from a nuclear power plant (carbon steel disposal: approx. 600 g), using a 240-liter decontamination solution (starting formic acid concentration: 2% (0.435 mol / L)) The sample liquid 240L of the contamination decontamination liquid (deterioration decontamination liquid) was prepared.
該試料液240Lを、下記仕様の電解槽(容量:40L)を用いて、下記条件でギ酸の電解再生を行なった。 240 L of the sample solution was subjected to electrolytic regeneration of formic acid under the following conditions using an electrolytic cell (capacity: 40 L) having the following specifications.
<電解槽>
陽極:市販イリジウム被覆チタン板(電極面積900cm2/枚×1枚、両面電極)
陰極:市販ステンレス板(電極面積900cm2/枚×2枚)
<電解条件>
平均電流値;11.5A(平均電流密度:0.06A)、 電解時間:60h、
なお、該試料液の処理前後のギ酸濃度及び鉄イオン濃度はそれぞれ、下記の如くであった。即ち、実用的なギ酸回復ができることが確認できた。更に、鉄(汚染金属)の回収率も良好であり、ギ酸の過酸化物分解に際しての沈殿物(鉄系酸化物)の生成量も少なく、後処理も容易となることが確認できた。
<Electrolytic cell>
Anode: Commercially available iridium-coated titanium plate (electrode area 900 cm 2 / sheet × 1 sheet, double-sided electrode)
Cathode: Commercially available stainless steel plate (electrode area 900 cm 2 / sheet x 2)
<Electrolysis conditions>
Average current value: 11.5A (average current density: 0.06A) Electrolysis time: 60h
The formic acid concentration and the iron ion concentration before and after the treatment of the sample solution were as follows. That is, it was confirmed that practical formic acid recovery was possible. Furthermore, it was confirmed that the recovery rate of iron (contaminated metal) was good, the amount of precipitate (iron-based oxide) produced during the decomposition of formic acid peroxide was small, and post-treatment was easy.
ギ酸濃度:再生前 0.72%→再生後 1.56%(回復率約78%)
鉄イオン濃度:再生前 7.75g→再生後 2.65g(回収率約66%)
Formic acid concentration: 0.72% before regeneration → 1.56% after regeneration (recovery rate approx. 78%)
Iron ion concentration: 7.75g before regeneration → 2.65g after regeneration (recovery rate approx. 66%)
11 除染槽
13 電解槽
15 除染液
27 電解陽極
29 電解陰極
31 汚染金属
DESCRIPTION OF
Claims (7)
該放射性金属廃棄物を、その金属塩が水溶性であり酸化分解可能な脂肪族カルボン酸を含む除染液に浸漬して、前記放射性金属廃棄物の表面部を脂肪族カルボン酸金属塩として前記除染液中に溶出させて除染を行う化学的除染操作を含む放射性金属廃棄物の処理方法において、
前記除染工程で発生する劣化除染液を電解して、陰極で前記カルボン酸金属塩の金属成分を析出させて回収するに際して、
陽極として導電性基体が白金族金属又は白金族金属酸化物で被覆されたものを使用して、脂肪族カルボン酸を電解再生させる、
ことを特徴とする放射性金属廃棄物の処理方法。 A method for treating ferrous radioactive metal waste whose surface is contaminated by radioactivity,
The radioactive metal waste is immersed in a decontamination solution containing an aliphatic carboxylic acid whose metal salt is water-soluble and oxidatively decomposable, and the surface portion of the radioactive metal waste is used as the aliphatic carboxylic acid metal salt. In a method for treating radioactive metal waste, including chemical decontamination operations, which are decontaminated by elution in a decontamination solution,
When electrolyzing the deteriorated decontamination solution generated in the decontamination step and depositing and collecting the metal component of the carboxylic acid metal salt at the cathode,
Electrolytic regeneration of aliphatic carboxylic acid by using a conductive substrate coated with a platinum group metal or platinum group metal oxide as an anode,
A method for treating radioactive metal wastes.
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2499025A (en) * | 2012-02-03 | 2013-08-07 | Nat Nuclear Lab Ltd | Decontamination of a system and treatment of the spent decontamination fluid |
EP3065139A4 (en) * | 2013-10-24 | 2017-06-28 | Kurita Water Industries Ltd. | Method and apparatus for treating liquid containing iron-group metal ions, method and apparatus for electrodeposition of co and fe, and method and apparatus for decontamination of radioactive waste ion exchange resin |
RU2646535C1 (en) * | 2017-04-12 | 2018-03-06 | Федеральное государственное унитарное предприятие "Научно-исследовательский институт Научно-производственное объединение "ЛУЧ" (ФГУП "НИИ НПО "ЛУЧ") | Method for nuclear production waste processing |
CN112908508A (en) * | 2021-01-12 | 2021-06-04 | 中国工程物理研究院材料研究所 | Method for treating radioactive analysis waste liquid by one-step method |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS60250300A (en) * | 1984-05-14 | 1985-12-10 | シーメンス、アクチエンゲゼルシヤフト | Method and device for treating solution for decontamination having organic acid |
JPS61204598A (en) * | 1985-03-07 | 1986-09-10 | 株式会社東芝 | Method of forming decontaminated liquid |
JPH0527093A (en) * | 1991-07-17 | 1993-02-05 | Hitachi Plant Eng & Constr Co Ltd | Processing of radioactive metallic sludge |
JPH10104396A (en) * | 1996-10-02 | 1998-04-24 | Toshiba Corp | Method and device for chemical decontamination |
JPH10123293A (en) * | 1996-10-18 | 1998-05-15 | Toshiba Corp | Method and device for chemical decontamination |
JP2002333498A (en) * | 2001-05-10 | 2002-11-22 | Toshiba Corp | Method of decontaminating radioactive substance |
JP2005528627A (en) * | 2002-06-01 | 2005-09-22 | バイオダイナミックス リサーチ リミテッド | New collection process |
JP2005315641A (en) * | 2004-04-27 | 2005-11-10 | Toshiba Corp | Treating method and treating device of decontamination waste liquid |
-
2008
- 2008-12-25 JP JP2008329688A patent/JP5253994B2/en not_active Expired - Fee Related
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS60250300A (en) * | 1984-05-14 | 1985-12-10 | シーメンス、アクチエンゲゼルシヤフト | Method and device for treating solution for decontamination having organic acid |
JPS61204598A (en) * | 1985-03-07 | 1986-09-10 | 株式会社東芝 | Method of forming decontaminated liquid |
JPH0527093A (en) * | 1991-07-17 | 1993-02-05 | Hitachi Plant Eng & Constr Co Ltd | Processing of radioactive metallic sludge |
JPH10104396A (en) * | 1996-10-02 | 1998-04-24 | Toshiba Corp | Method and device for chemical decontamination |
JPH10123293A (en) * | 1996-10-18 | 1998-05-15 | Toshiba Corp | Method and device for chemical decontamination |
JP2002333498A (en) * | 2001-05-10 | 2002-11-22 | Toshiba Corp | Method of decontaminating radioactive substance |
JP2005528627A (en) * | 2002-06-01 | 2005-09-22 | バイオダイナミックス リサーチ リミテッド | New collection process |
JP2005315641A (en) * | 2004-04-27 | 2005-11-10 | Toshiba Corp | Treating method and treating device of decontamination waste liquid |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2499025A (en) * | 2012-02-03 | 2013-08-07 | Nat Nuclear Lab Ltd | Decontamination of a system and treatment of the spent decontamination fluid |
EP3065139A4 (en) * | 2013-10-24 | 2017-06-28 | Kurita Water Industries Ltd. | Method and apparatus for treating liquid containing iron-group metal ions, method and apparatus for electrodeposition of co and fe, and method and apparatus for decontamination of radioactive waste ion exchange resin |
US10083769B2 (en) | 2013-10-24 | 2018-09-25 | Kurita Water Industries Ltd. | Treatment method and treatment apparatus of iron-group metal ion-containing liquid, method and apparatus for electrodepositing Co and Fe, and decontamination method and decontamination apparatus of radioactive waste ion exchange resin |
RU2646535C1 (en) * | 2017-04-12 | 2018-03-06 | Федеральное государственное унитарное предприятие "Научно-исследовательский институт Научно-производственное объединение "ЛУЧ" (ФГУП "НИИ НПО "ЛУЧ") | Method for nuclear production waste processing |
CN112908508A (en) * | 2021-01-12 | 2021-06-04 | 中国工程物理研究院材料研究所 | Method for treating radioactive analysis waste liquid by one-step method |
CN112908508B (en) * | 2021-01-12 | 2022-11-04 | 中国工程物理研究院材料研究所 | Method for treating radioactive analysis waste liquid by one-step method |
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